I'd expect a line DC problem, or ground loop, to start immediately. Hum coming later sounds more like failing capacitors to me. You could try a DC blocker to see if it helps.
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A DC Blocker to help stop transformer HUM
- Thread starter Colin James Wonfor
- Start date
Seems to be correct, I dug out an old Emotiva CMX-2 I bought over 10 years ago and left in storage and it appears all the noise is gone now. Interesting, I actually bought the thing because I thought it looked nifty but got annoyed due to the lack of outlets, somehow it turned out its actually pretty useful.
Almost certainly not. A DC blocker helps with DC, and DC doesn't magically appear or disappear when playing music or after having your system on for a certain amount of time. It may come and go on the line but would do so independently of what you do with your music (do you play with crappy dimmers and high powered lighting, is the wife drying her hair with the hairdryer on the low setting, do you have a dodgy fridge compressor, etc, etc).
Other things can cause hum such as uneven loading of the transformer windings. Most likely a failing capacitor or a failing diode in the bridge rectifier.
An Isolation transformer will block out DC offset. And it does it very very effectively. Then you may ask, "well the isolation transformer will hum itself from the DC offset." A well designed toroidal will not hum from DC offset.
I have few Emotiva CMX-2, but it's only 2 outlets. Why the f would Emotiva not design one that is 6 outlets?
Anyway, that is why I have a Torus isolation transformer, it has 8 outlet and it works superbly. However, the problem with isolation transformer is that (well there are 2 problems) it consumes a lot of power when idle. The one that I have, I measured it at 175w when idle. The other problem is that an isolation transformer of that size has a huge transformer and the magnetic field is VERY strong. I don't feel comfortable being around something with this strong of magnetic field, anyone saw X-Men when Magneto mutated everyone in NY? However, the EMF, is easily addressed by shielding the toroidal with mu metal, it is super effective, which is what I did.
I have since retired my Torus, until if and when I get solar panels.
Until then, I am on the market for a 6 outlet DC blocker or a DC blocker that is capable of 15A so that I can plug a strip to it.
I have few Emotiva CMX-2, but it's only 2 outlets. Why the f would Emotiva not design one that is 6 outlets?
Anyway, that is why I have a Torus isolation transformer, it has 8 outlet and it works superbly. However, the problem with isolation transformer is that (well there are 2 problems) it consumes a lot of power when idle. The one that I have, I measured it at 175w when idle. The other problem is that an isolation transformer of that size has a huge transformer and the magnetic field is VERY strong. I don't feel comfortable being around something with this strong of magnetic field, anyone saw X-Men when Magneto mutated everyone in NY? However, the EMF, is easily addressed by shielding the toroidal with mu metal, it is super effective, which is what I did.
I have since retired my Torus, until if and when I get solar panels.
Until then, I am on the market for a 6 outlet DC blocker or a DC blocker that is capable of 15A so that I can plug a strip to it.
All of the medical grade isolation transformers I've bought all hum like a bitch, and many of them are super expensive going into the hundreds of dollars. I find the passive DC offset devices better and more cost effective. The Emotiva CMX-2 might only have 2 outlets, but most of the DIY kits online (including the one suggested in this thread) only have 1 (one!). So we can only take what we can get haha.
Toroidal transformers tend to constrain the magnetic field to the donut-shaped core, much better than the E-I stacked laminated ones do to their cores. Your exposure to a magnetic field is tiny once you are a few inches away from either type of transformer, especially the toroid, and even near it, it's no big deal. Of course, I am talking about transformers in consumer equipment, not power stations.
The theory is correct. However, I have a fairly decent EMF meter at home, don't ask me why and how. Anyway, based on my measurements, few inches is way too optimistic. And the numbers I see on the meter, does not make me comfortable, if I remember correctly, at about 8 inches away, it was like 30 guass. High enough for me to use mu metal for shielding.
EMF meters indicate the presence of radio frequency interference (RFI), not isolated magnetic fields. There is a magnetic component to RFI, but it is exceedingly small. You need a magnetometer to do measure what you are looking at. Perchance, that is the type of meter you may be using. If that's true, then that seems like a rather high magnetic field.
You know what, I don't remember if the unit of measure is guass or milliguass is being displayed. I just remembered that "the goal is to keep it under 1."
I'll take a look at the meter tonight.
And I'm confused why the EMF meter wouldn't be applicable.
If you have an EMF meter, the units will be in volts per meter. A magnetometer will have units in gauss. As for 1 gauss, the earth's magnetic field is almost 1 gauss.
Voltage field strength meters for power line emissions and RFI are fairly common; magnetic field strength meters much less so IME. I have no idea what you have, of course, but odds favor @egellings hypothesis.
Again IME, toroidal transformers are much more sensitive to DC saturation compared to EI or other types, due to the toroid's lack of a core gap. The one or two big (15~20 A) units I have seen actually included the usual diode/capacitor DC blocking circuit before the isolation toroid.
Again IME, toroidal transformers are much more sensitive to DC saturation compared to EI or other types, due to the toroid's lack of a core gap. The one or two big (15~20 A) units I have seen actually included the usual diode/capacitor DC blocking circuit before the isolation toroid.
Every phone has a 3 axis one
Where, used for what? Not disputing it, curious. I don't think putting my phone near a magnet has confused it, but not something I do often (I have done it, though, and do not recall any adverse effects).Every phone has a 3 axis one
Edit: OK, found this article (and many others): https://www.techfow.com/does-my-phone-have-a-magnetometer-fact-checked/
Which jogged my memory about reading about them years ago. Not all of them have one, however; there are other schemes for positional and navigational sensing.
Magnetometers are used for things like dead reckoning, compass or other sensor fusion stuff. There are also apps to find hidden electrical wires.
Your compass app can be influenced by a magnet, but usually the effect is temporary. One can filter these things out with a bit of math.
Yah, I was curious and found several articles online, which led me back to a couple I had saved myself.
Still, I have not seen as many stand-alone (handheld) magnetic field sensors as electrical field sensors in the wild, but that may purely reflect my career focus on electrical stuff more so than magnetic. Knew I should have gotten a BS Magnetic Engineering...
Mine is measures in gauss. I think its unit is milliguass, I have to double check. The display doesn't specify the unit of measure and only provides the number. So I probably just mistaken/misspoke it to be gauss.
I'm not saying this source here is any form of authority, but they describe: "EMF meters can measure both AC electromagnetic fields (sometimes referred to as Gauss meters or Magnetometers) or DC fields." When I broughty meter it was described as an EMF meter. Perhaps it's incorrect.
What is an EMF Meter?
Wouldn't that 3-axis sensor in a phone be an accelerometer, rather than some sort of RFI sensing device? I'm not aware of 3-axis magnetometers or RFI meters, although I could be wrong on that.Every phone has a 3 axis one
Usually both are present, as well as a gyro, giving 9 axis measurements of magnetism, acceleration and angular velocity.
Single chip solutions exist, like this one:
ICM-20948 | TDK InvenSense
The ICM-20948 is the world’s lowest power 9-axis MotionTracking device that is ideally suited for Smartphones, Tablets, Wearable Sensors, and IoT applications. 1/3 the power of existing 9-axis devices 3-axis gyroscope, 3-axis accelerometer, 3-axis compass, and a Digital Motion Processor™ (DMPTM)...
invensense.tdk.com
I looked that up. Amazing!Usually both are present, as well as a gyro, giving 9 axis measurements of magnetism, acceleration and angular velocity.
Single chip solutions exist, like this one:
ICM-20948 | TDK InvenSense
The ICM-20948 is the world’s lowest power 9-axis MotionTracking device that is ideally suited for Smartphones, Tablets, Wearable Sensors, and IoT applications. 1/3 the power of existing 9-axis devices 3-axis gyroscope, 3-axis accelerometer, 3-axis compass, and a Digital Motion Processor™ (DMPTM)...
This is the one I got. It literally saids milliguass right on it.
Anyway, the Torus had a really strong magnetic field even at about 2 feet away. It was high enough where it did not make me feel comfortable. Mu Metal does the trick, it significantly attenuates it, and it's not like mu metal is toxic, so it can only help and it can't harm, absolutely zero brainer. There are other metal alloys like mu metal you can use.
AC Milligauss Meter UHS2
Gauss meter for precise measurement of AC magnetic fields
www.alphalabinc.com
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